It's a revolution of joint rejuvenation

We're becoming a nation of bum knees, worn-out hips and sore shoulders, and it's not just the Medicare set. Baby boomer bones and joints also are taking a pounding, spawning a boom in operations to fix them.

Knee replacement surgeries have doubled over the past decade and more than tripled in the 45-to-64 age group, new research shows. Hips are trending that way, too.

And here's a surprise: It's not all due to obesity. Ironically, trying to stay fit and avoid extra pounds is taking a toll on a generation that expects bad joints can be swapped out like old tires on a car.

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"It's this mind-set of 'fix me at any cost, turn back the clock,'<2009>" said DiNubile, an adviser to several pro athletic groups and a spokesman for the American Academy of Orthopaedic Surgeons. "The boomers are the first generation trying to stay active in droves on an aging frame" and are less willing to use a cane or put up with pain orfness as their grandparents did, he said.

A huge industry says they don't have to. TV ads show people water skiing with new hips. Ads tout "the athletic knee," "the custom knee," "the male knee," "the female knee." Tennis great Billie Jean King, 67, is promoting the "30-year" Smith & Nephew knees she got last year.

"I wanted to make sure whatever they put in me was going to last," King said. "I'm not trying to win Wimbledon anymore. I'm trying to get my exercise in," play a little tennis on the clay courts in Central Park, and walk to a movie or a restaurant. "If I'd known what I know now, I would have had it 10 years ago."

Joint replacements have enabled millions of people like King to lead better lives, and surgeons are increasingly comfortable offering them to younger people.

But here's the rub: No one really knows how well these implants will perform in the active baby boomers getting them now. Most studies were done in older folks whose expectations were to be able to go watch a grandchild's soccer game -- not play the sport themselves, as one researcher put it.

Even the studies presented at a recent orthopedics conference that found knee replacements are lasting 20 years come with the caveat that this is in older people who were not stressing their new joints by running marathons, skiing or playing tennis.

"We think very carefully about patients under 50" and talk many of them out of replacing joints, said Dr. William Robb, orthopedics chief at NorthShore University HealthSystem in suburban Chicago.

Dr. Ronald Hillock, an orthopedic surgeon in a large practice in Las Vegas that does about 4,000 joint replacements a year, sees the demand from patients.

"People come in and say, 'this is what I want, this is what I need,'<2009>" he said. "They could buy a cane or wear a brace," but most want a surgical fix.

umbers tell the story. There were 288,471 total hip replacements in 2009, nearly half of them in people younger than 65, according to the federal Agency for Healthcare Research and Quality, which tracks hospitalizations.

Knee replacements soared from 264,311 in 1997 to 621,029 in 2009, and more than tripled in the 45-to-64-year-old age group.

"Five or 10 years ago, a very small number of people under 65 were receiving this surgery. Now we see more and more younger people getting it," said Elena Losina, co-director of the Orthopaedic and Arthritis Center for Outcomes Research at Brigham and Women's Hospital in Boston.

She analyzed how much of this rise was due to population growth and obesity, and presented results at an orthopedic meeting in San Diego in February.

From 1997 to 2007, the population of 45- to 64-year-olds grew by 36 percent, but knee replacements in this group more than tripled. Obesity rates didn't rise enough to explain the trend.

"At most, 23 percent of the 10-year growth in total knee replacement can be explained by increasing obesity and population size," Losina said.